| 摘要 |
<p>[Problem] A sensor with an optical interference signal output as a sensor signal uses a homodyne interference scheme with a simple configuration and the sensor portion being capable of not having a built-in power source. To obtain reliable operation, however, strict work precision with respect to the used components and thermal expansion countermeasures are required. Also, the phase range in which fluctuation as a sensor signal is possible has been limited to within ±90°. [Solution] Provided is an optical fiber sensor wherein: with input from an interferometer being a periodic optical pulse, and the phase in the first half and the latter half of a reference optical pulse differing by 90° (quadrature phase), causing interference with a measured optical pulse, two interference output values (i1, i2) which differ by 90° are obtained; from the values (r, s) of the optical reference and the optical measurement, and with the phase difference between the optical reference and the optical measurement designated ?, two cosine values (cos?1, cos?2) are computed, locations designated upon a cosine curve, and angles (?1, ?2) are derived, thereby, effects of optical interference intensity fluctuations and phase operation point fluctuations are eliminated; the differences with the angles of the immediately previous period are added and made to be sensor output, and as a result, the phase range in which sensor signal fluctuations are allowed may exceed ±90° (half-wavelength).</p> |
